The WLCSP technology is a technology in which a whole wafer is packaged and tested first, and then diced into individual chips. Such a technology is totally different from conventional packaging technologies such as Chip on Board (COB), where a whole wafer is thinned and diced into individual chips, and then the chips are wire bonded. The size of a chip after being packaged with the WLCSP technology is the same as that of the bare chip. The WLCSP technology satisfies the requirements for the microelectronic products, such as light weight, small size (especially in length and thickness) and low cost. A chip packaged with the WLCSP technology realizes its miniaturization, and the chip cost decreases significantly with the decrease of the chip size and the increase of the wafer size. The WLCSP technology, which, when being implemented, can take into account the IC design, wafer fabrication, packaging test and substrate fabrication in combination, is a focus in the packaging field and one of the development trends of the packaging technologies.
With the increase of the chip size, the machine station and other parts of the WLCSP apparatus need to be enlarged correspondingly or the whole WLCSP apparatus needs to be replaced with a new one. Thus, the cost for updating the WLCSP apparatus increases significantly.
In addition, a crack often occurs during the wafer fabrication. If a wafer with a crack is packaged with the conventional WLCSP technology, the crack may be prolonged.